Partial :object vs instance var

rubyonrails-talk
1

I'm questioning what appears to be a recommendation that makes no sense in AWDWR 2nd Ed. I get the point being made, but the actual convention/implementation seems to make the point ineffective.

  -- In the layout, we have access to the @cart instance variable that was set by the controller. It turns out that this is also available inside partials called from the layout. However, this is a bit like calling a method and passing it some value in a global variable. It works, but it's ugly coding, and it increases coupling (which in turn makes your programs brittle and hard to maintain).

This is a good point. I don't recommend using instance variables in partials. Everything should be passed to the partial from the template. Treat a partial like a subroutine that can be called in different contexts and that you pass arguments to.

2

You can do that, but it would be

  x['infoA'].someAttr

Preferred is to pass multiple values using :locals

  render :partial => 'x', :locals => {:infoA => objectA, :infoB => objectB}

Then in the partial, you have reference separate variables:

   infoA.someAttr    infoB.someAttr

3

May I use :collection and :locals together to handle parameters while rendering partial?

Thanks!

4

Yes.